This invention relates to masking tape for use in spraying automobile doors and the like openings to prevent penetration of spray through thexe2x80x94as yetxe2x80x94unsealed gap between door (or other opening member, such as sun roof) and surround.
Masking tapes for such use are known in various forms made of foam material such for example as polythene, polyester, neoprene and the like. GB 885 660 discloses strip on tape of square cross-section, which is compressed and then fitted into channels provided for subsequent fitting of weather sealing strip. EP 0 365 510 discloses strip of rectangular cross-section as well as strip of circular cross-section with adhesive on one face of the rectangular section embodiment and covering one side of the circular section embodiment.
Widely used are strips which are essentially ribbon-like which are readily folded or bent into a C-cross-section. These ribbon-like tapes have adhesive on one side for attachment to the fixed structure.
Despite the continued development of these masking tapes, problems are experienced in use. For one thing, they need to be applied carefully so as to be correctly positioned. Often, mispositioning is not apparent until the door or other member has been closed andxe2x80x94worsexe2x80x94maybe not even then. Exposed adhesive, for another, prevents absorption and paint builds up which hardens into an edge that has to be rubbed down.
The present invention provides masking foam tapes which do not suffer from these problems.
The invention comprises a masking foam tape adapted for use in spraying automobile doors and like openings to prevent penetration of spray through the unsealed gap between door and door surround, having an elongate, substantially rectangular section having major dimension at least twice but not more than four times its minor dimension and having at one end of its elongate section adhesive for attachment at the opening and being tapered and free of adhesive at the other end thereof.
The adhesive may be only on one face of the tape having the major dimension.
The tapered end may be rounded or faceted, and may be made by extrusion through an appropriately shaped die or by crush cutting and thereby cold welding so as to make two tapes out of a single wider tape, each with a cold welded, rounded edge.
The tapered end may be on a lateral projection, which may be, in length, substantially the same as the minor dimension of the substantially rectangular section.
The tape may have adhesive as one face only, the lateral projection being from that face.
The lateral projection may be necked.
The tape may have adhesive on one face only, and lateral projections from both faces.
The tape may have its substantially rectangular section slightly tapered towards its adhesive end so as to have (except for its adhesive-free, tapered end) a slightly trapezoidal section.
A tape, even without a lateral projection, may be necked at its tapered adhesive-free end.
Conventionally, automobile doors, when sprayed in situ in the door surround, are masked by a self-adhesive foam masking strip or tape which is adhered around the surround, the door being then closed on it to trap the strip so as to prevent ingress of spray paint into the automobile interior. If two coatsxe2x80x94primer and top coatxe2x80x94are to be applied, best practice requires that the mask be peeled off and any hard edges of primer rubbed down before re-masking and top coat application. A problem arises, when primer and top coats are being applied, in that on surfaces within the gap between the edge of the door and the surround, the area covered by the primer is not necessarily the same as that covered by the top coat, which leaves an untidy appearance.
The present invention provides a method for masking during painting and a masking tape for use therein, avoiding these problems.
The invention also comprises a paint masking strip comprising a body part with adhesive for attachment to a workpiece and a readily separable part.
The separable part may comprise a tear-off part, which may be integral with the body part, joined by a thin web or adhesively attached to the body part.
The body part may have an oblong cross-section with a strip of adhesive at one edge of a wider face, the separable part being at the other edge of said face. The ratio of the width of the wider and narrower faces may be between 2:1 and 5:1. The body part may be tapered at the said other edge.
The tear-off part may be a bead of width equal to the width of the narrower face of the body part.
The body part may have a lateral projection from the face which bears the adhesive and at the opposite edge of said face, and the separable part may then be on that projection.
The strip may, however, comprise a readily foldable ribbon-like body part, the removable part being along one face thereof, intermediate its edges. The removable part may comprise a bead which is narrow by comparison with the width of the body part. The bead may be closer to one edge of the strip than the other, and the said one edge may have an adhesive strip on the same face as the bead. The opposite face of the body part may have an adhesive strip at its opposite edge.
The strip may be made of open-cell foam material.
The invention also comprises a method for masking an unsealed automobile door or like opening for spraying, comprising attaching a tape according to the invention above-stated around the inner edge of the open door or other opening member to project around the door or member beyond the rim thereof and closing the door or member to position the projecting part of the tape between door or member and surround, and, where necessary, subsequently adjusting the said part of the tape to be evenly accommodated around the rim.
As the tapered edge of the tape, which is effectively the sealing portion thereof being, when closed on, trapped between the surround and the door or other member rim, has no adhesive, it can readily be adjustedxe2x80x94the trapping action leaving scope for manual adjustment where the foam might project too far out of the gap, or not far enough. Moreover, the whole exposed surface is absorbent and causes no hard edge formation, saving a rubbing-down operation which is time consuming.
The invention also comprises a method for masking during painting the outer face of a door in a door surround comprising attaching a mask between door and surround to seal against penetration of paint through the door opening, the masking having a readily removable part which protrudes from between the edge of the door and the surround, painting the door and surround with a first coat of paint, removing the readily removable part of the mask, then painting the door and surround with a second coat of paint.
The mask may be adhesively attached to the door which is then closed to trap the mask between door and surround.
Foam masking tapes are usually supplied in roll form. In order to attach to the vehicle they are provided with an adhesive strip, perhaps more than one. In roll form, there is, however, a tendency for the adhesive to adhere to the adjacent layer of tape on the roll. This tendency can of course be counteracted by winding the roll with an interleaved release paper, which is, on use of the tape, wastefully discarded and which might well interfere with the efficient use of the tape. The other method for avoiding interlayer adhesion is so to adjust the tack of the adhesive that it does not adhere to the adjacent foam layer at the interlayer pressure in the roll, yet adheres satisfactorily to the vehicle""s surface. This requires control of both tack and winding tension with obvious opportunities for error and customer complaint. Another factor is, of course, shelf life, the adhesive characteristics being required to change within but narrow limits during a reasonable shelf life and, for best practice, the imposition of some system of stock control, with sell-by and use-by dates to be taken into account by both distributor and end-user.
The present invention provides a solution to these problems.
The invention comprises a compressible foam product stored in layers and having an adhesive by which it is adapted, in use, to be attached to a surface, the adhesive being so arranged as to be between adjacent layers but out of contact with the next adjacent layer in the store.
The layers may be layers of a roll of strip or sheet foam material, or layers of a stack of strip or sheet foam material pieces.
The adhesive may be contained within a depressed region or regions of the product, or may face a depressed region or regions of the product, so as to remain out of contact.
When the product is a paint masking tape the adhesive is usually in the form of a length-wise strip, which may, according to the invention, be in a groove of the material or opposite a groove of the next adjacent layer in the roll or stack.
Clearly, when the adhesive is on the surface, against a corresponding depression in the adjacent face in the roll or stack, there is no problem whatever in use.
When the adhesive is itself sunk in a groove, it is only necessary that ordinary pressure for application of the material to the desired surface pops the adhesive out to contact the surface and the tack is sufficient to hold the adhesive in position against any resilience of the foam, the other normal requirement, of course, being that the material, its job done, can be stripped from the surface.